Antimicrobial Activity and Mechanism of Action of Dracocephalum moldavica L. Extracts Against Clinical Isolates of Staphylococcus aureus

Abstract

Background: Dracocephalum moldavica L. is a popular traditional medicine used by many countries, which has a wide range of pharmacological effects. The aim of this work was to investigate the antimicrobial effects of D. moldavica L. extracts against clinical isolates of Staphylococcus aureus . Our results demonstrated that the minimal inhibitory concentration (MIC) for 50 and 90% of S. aureus isolates (MIC 50 and MIC 90 ) of the ethyl acetate (EtOAc) fraction from D. moldavica L . ethanol extract were 780 and 1,065 μg/ml, respectively. We further observed that the EtOAc fraction disrupted 24-h biofilm caused cell membrane damage and irregular cell shape. Additionally, the EtOAc fraction showed slight to moderate toxic effects on human epidermal keratinocyte (HaCaT) cells. Moreover, the results of the differential proteome revealed that 231 proteins were upregulated, while 61 proteins were downregulated in S. aureus after treatment with the EtOAc fraction. The differentially expressed proteins were functionally categorized by the Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. These proteins contribute to membrane damage, inhibition of biofilm formation, and changes in energy metabolism. Thus, the EtOAc fraction of D. moldavica L. ethanol extract, as a natural product, has the potential to be used as an antimicrobial agent to control the clinical isolates of S. aureus .

UPLC–PDA‐ESI–QTOF–MS/MS and GC‐MS analysis of Iranian Dracocephalum moldavica L.

“…None of the extracts (50-400 μg.ml -1 ) exhibited cytotoxic activity, suggesting potential safety of the plant. This is in accordance with a study by Yu et al, (2019) who did not found a significant cytotoxic effect of the EtOAc extract of D. moldavica (33.3% growth inhibition at 100 μg.ml -1 ) against human epidermal keratinocyte (HaCaT) cells. To the best of our knowledge, there is no other published data on the cytotoxicity of D. moldavica extracts.…”

Isolation and Characterization of a New Endophytic Actinobacterium Streptomyces californicus Strain ADR1 as a Promising Source of Anti-Bacterial, Anti-Biofilm and Antioxidant Metabolites

“…Similarly, in a study on the effect of antibiotics like rifampicin, polymyxin B, kanamycin and doxycyclin on reduction of S. aureus biofilm formation, only rifampicin was found to inhibit the biofilm by about 50% [56]. The effect of ADR1 metabolites on inhibition of biofilm formation as well as on the preformed biofilms was better than some previously reported metabolite extracts [57][58][59]. Inhibition of biofilm formation strongly suggested that the metabolites prevented adherence of S. aureus and MRSA cell to the polystyrene surface.…”

Genipin in an Ex Vivo Corneal Model of Bacterial and Fungal Keratitis

“… 101 In an effort to meet the urgent need for new antimicrobial drug discovery and development, in recent years a lot of attention has been paid to natural products and medicinal plants due to their low toxicity, pharmacological effects and health benefits. 102 , 103 Among natural product-derived compounds, genipin has received particular attention in ophthalmology because of its effective crosslinking activities. 59 – 69 In this study, the in vitro antimicrobial effects of genipin were evaluated against clinical isolates of S. aureus, P. aeruginosa and C. albicans using an ex vivo model of corneal infectious keratitis.…”